Electric glow valve system



Sept. 26, 1939. A. J. McMAsTER ET AL 2,174,500

ELECTRIC GLOW VALVE SYSTEM Filed Sept. 5, 1936 2 Shoots-8hoet l L fj Sept. 26, 1939.

A. J. MQMASTER n AL ,500

ELECTRIC snow VALVE SYSTEM 2 Sheets-Sheet 2 Filed Sept. 5. 1936 Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE ELECTRIC GLOW VALVE SYSTEM of Illinois Application September 5, 1936, Serial No. 99,674 18 Claims. (Cl. 250-27) Our present invention relates generally to electric control systems and relates more particularly to systems employing glow valves or the like, especially, diode glow valves.

A glow valve is a space discharge device and generally consists of two or more electrodes immersed in a gaseous medium contained within a suitable inclosure for confining the gas thereof at a suitable pressure.

A glow valve is so called because its gas emits an iridescent glow when current is conducted therethrough between the electrodes. The current passed by such a valve is conducted therethrough by a flow of gaseous ions in the interelectrode space, the gas being under a condition of sustained ionization. When the current is interrupted the gas deionizes by recombination 01' ions except for a small degree of ionization known as the residual ionization. In this idle condition the valve exhibits a high impedance because there are not suflicient ions present to produce an appreciable current. When the voltage across the electrodes is raised to a millciently high value, known as the striking voltage, the voltage gradient in the interelectrode space becomes so high that the rate of ionization by collision resulting from the presence of residual ions exceeds the rate of accidental recombination and a condition of sustained operation is precipitated. This is accompanied by the initiation of a substantial current and its concomitant glow and therefore by a reduction of the impedance oi the valve. It is a condition of sustained ionization, or sustained glow operation, of the valve and when established, that condition can be maintained at a voltage considerably less than the ignition voltage defined above. The lower limit of the range of voltages at which glow operation will be maintained is known as the extinguishing voltage. Obviously the extinguishing voltage is lower than the ignition voltage. When the voltage impressed across the electrodes drops below the extinguishing value, the rate of ionization falls below the rate of recombination of ions and the valve ceases to pass current. That is, its glow operation is interrupted, and its impedance returns to a high value. A glow valve will ignite upon receiving high voltage for a very short period of time and thereafter will maintain its operation ii a voltage above its extinguishing voltage, is maintained.

Glow valves frequently are employed in systems where it is desired to prolong the eflect of an electric disturbance, impulse or signal. Thus a brief or transient signal may serve to ignite a valve which thereaiter continues to glow so as to operate a relay or the like whichrequires a period of time for its operation far in excess of the duration of the signal.

For example, a glow valve may be employed to advantage with photoelectric register control equipment in which a photoelectric cell is illuminated by light reflected from, or transmitted through, a moving web of strip material, such as paper, and in which printed reference marks coming periodically into the light beam induce signals in the photoelectric cell. These signals may be amplified and also timed" by an interrupter to determine whether the strip material is in proper register with the machine through which it is passing. The signals ignite the glow valve to control the adjustments necessary to bring the material into register. This serves to keep successive printing operations, -or printing and cutting operations or the like in proper register with each other.

The most advantageous amplification of a signal for the purpose of igniting a glow valve usually requires a coupling arrangement between the amplifier and glow valve such that a high impedance is presented thereby to the glow valve. Heretofore this has proven to be a disadvantage in the operation of glow valves of the diode type since, in systems heretofore known, the diode glow valves were required to pass their glow currents through their signal input devices. A diode glow valve, while it lacks the inherent high sensitivity and self amplification of a grid controlled glow valve, does possess a greater degree of stability and in that respect is superior to the grid controlled type for certain uses. While the present invention is particularly directed to the improvement of systems employing diode glow valves, it, also, may be used under certain conditions with other types of glow valves.

It is a primary purpose of the present invention to provide an improved system for the control of a glow valve by an electronic amplifier for the operation of a relay or the like.

It is a further object to provide a simple and cheap, but eflicient and reliable glow valve system.

It is a further object to increase the eflectiveness of a signal for igniting a glow valve by subjecting it to voltage amplification in a high ratio transformer.

It is a further object of our invention to improve the operation of a glow valve for the control of a magnetic relay or the like by altering its circuit conditions in response to the ignition of the valve so as to permit a greater glow current to flow than can flow under those conditions which permit a reliable and sensitive control of the ignition of the valve.

It is a still further object of our invention to provide means other than the valve itself which will be responsive to the glowing of the valve for increasing the voltage-to-impedance ratio of the circuit containing the anode and cathode of the valve.

It is a still further object of our invention to provide means for separately adapting the circuit of a diode glow valve to each separate function which it is required to perform so that the valve operates to its best advantage both when receiving a signal for its ignition and when glowing to operate a relay or the like.

A further object is the provision of an improved system embodying a glow valve.

These and other objects and advantages will appear as the description proceeds.

In order better to acquaint those skilled in the art with the teachings and the practice of our present invention, we now shall describe certain specific embodiments thereof, reference being had to the accompanying drawings which form a part of this specification, and in which: Figs. 1 and 2 are circuit diagrams of photoelectric amplifier and relay systems employing diode glow valves and embodying our present invention; Fig. 3 illustrates a similar system embodying our present invention in its preferred form; and Fig. 4 illustrates a modification of the system of Fig. 3.

In Fig. 1, a photoelectric cell H1 is illuminated by a lamp or light source The light from the lamp II is focused by a lens |2 into the plane of a moving web of strip material l3, the light passing therethrough to irradiate the light sensitive cathode l4 of the photoelectric cell If). The web |3 carries a series of relatively opaque reference marks l5 which are so arranged as to pass into the light beam as the strip progresses so as to diminish or substantially interrupt the illumination of the cathode 4 of the photoelectric cell ID. The cathode l4 and anode l6 of the photoelectric cell are connected to the in-put terminals l1 and I8 respectively of an amplifier and relay unit indicated generally by the reference numeral 20. The amplifier comprises a pentode amplifying valve 2| coupled to an impulse transformer 22.

Power for the operation of the entire system including the pentode 2| of the amplifier is obtained from a transformer which is designated generally by the reference numeral 23 and which has a primary winding 28. The system of Fig. 1 preferably includes three separate power supplies having rectifiers and filters all powered by the transformer 23. The power supply for the pentode valve 2| is designated generally by the reference numeral 25 and includes a diode rectifier valve 24 and a conventional filter net. The positive terminal of the out-put of the power supply 25 is designated by the reference numeral 26 and the negative terminal thereof by the reference numeral 21. The anode 29 of the pentode amplifying valve 2| is connected to the positive terminal 26 of the power supply 25 through the primary winding 30 of the impulse transformer 22 and a milliammeter 33. The screen grid 3| of the pentode 2| is connected directly to the terminal 26 so that it remains at substantially constant potential for shielding the control grid 32 from the effect of varying potentials of the anode 29 in a manner well known in the art.

A high resistance 35 is connected in series with the photoelectric cell l0 between the negative terminal 21 of the power supply and the anode 29 of the valve 2| to supply to the photoelectric cell the voltage required for its operation, the cathode l4 of the photoelectric cell being connected to terminal 21 and the anode l6 thereof being connected to the resistor 35. The anode l6 of the photoelectric cell is connected, also, to the control grid 32 of the pentode amplifier 2|. A bleeder 36 is connected across the terminals 26 and 21 of the power supply 25; and a tap 31 of the blceder is connected to the cathode 38 of the amplifier 2|. An adjustment of the tap 31 of the bleeder 36 serves to control the difference of potential between the cathode 38 and control grid 32- of the valve. This is commonly referred to as the bias potential of the valve. The tap 31 should be adjusted to provide a low anode current as indicated by the milliammeter 33 when no reference mark l5 obstructs the beam of light focused on the photoelectric cell I0. Thus if the valve 2| saturates at about l5 milliamperes, the current may be set at 1 milliampere. When one of the reference marks l5 darkens the cell ID, the anode current of the valve 2|, as shown by meter 33 will increase.

A cathode grid 40 which serves to suppress secondary emission from the anode 29 in valve 2| is connected directly to the cathode 38 within the valve itself. A filament heater 4| for the cathode 38 of the valve 2| receives power from one of the windings of the transformer 23.

The impulse transformer 22 has an exceedingly high step-up ratio. It is desirable to secure as much signal amplification as possible in the transformer 22 and-to this end it is given as high an impedance ratio as is possible. As is well known, the impedance that may be provided in such a winding is limited in part by the presence of capacity between the individual turns of the winding.

The secondary winding 42 of the transformer 22 is connected. in series with a diode glow valve 45, the coil 46 and contacts 48 of a relay 41, a timer or interrupter 50 and a power supply 53 having terminals 5| and 52. shunting the contacts 48 of the relay 41, is a circuit through a resistor 54 and a power supply 51 having terminals 55 and 56. Additional contacts 49 of the relay 41 are provided for the purpose of controlling a load circuit in any known manner. Each of the power supplies 53 and 51 includes a secondary winding of the transformer 23, a diode rectifier, and a filter net. The two diode rectifiers of the power supplies 53 and 51 are represented as being within a common envelope.

The operation of the system of Fig. 1 is as follows: The voltage between the terminals 5| and 52 is arranged to be less than the ignition voltage of the diode glow valve 45 but in excess of the extinguishing or minimum, operating voltage thereof. The interrupter 50 periodically opens and closes the circuit through the glow valve 45. The web l3 continually passes through the beam of light which illuminates the cathode l4 of the photoelectric cell In, and in so doing suddenly interrupts a substantial portion of the light flux each time that one of the reference marks l5 enters the light beam. This sudden change of illumination controls the amplifier valve 2| to produce a sudden change in its plate current or anode current which flows through the 75 primary winding SI of the impulse transformer 22. 'ihissuddenchanleofprimarycurrentof the transformer produces a high voltage signal in the secondary winding 42; and if the interrupter ll is closed at the time of the signal, the signal is impressed across the glow valve 45. This signal either adds to or subtracts from the voltage appearing at the terminals 5| and 52 depending upon the relative polarities of the various connections of the circuit.

As the reference mark 15 leaves the light beam, the light flux incident on the photoelectric cell suddenly increases and acts through the ampliiier 2| and transformer 22 to impress another signal on the glow valve of a polarity opposite to that of the first signal.

One of these two signals will be of the proper polarity to add itself to the voltage appearing at the terminals 5| and 52 of the power supply 53. The voltage of the signal is of sufliciently high value that when it is added to the voltage of the power supply 53 the total voltage impressed across the electrodes of the diode glow valve 45 is sufncient to ignite the valve. That is, it is sufiicient to initiate a sustained glow operation of the valve 45. Immediately that the tube 45 begins to glow, current traverses the coil 46 of the relay 41 causing the relay to operate.

Because of the necessarily high impedance of the secondary winding 42 of the transformer 22, and because it is necessary to limit the voltage of the power supply to some value below the ignition voltage of the valve 45, the current which initially passes through the relay -coil 45 when the valve 45 glows, is limited. As soon as the relay 41 begins to operate, it opens its contacts 45 so that the current of the valve 45 flows through the resistor 54 and the power supply 51. This places the two power supplies 53 and 51 in series in the glow valve circuit with their voltages adding. It, also, adds the resistance 54 to the glow valve circuit. The voltage of the power supply 51 may be as high as necessary for supplying suflicient current for satifactory operation of the relay 41. The resistor 54 need have only a high enough resistance to avoid drawing too much power from the power supply 51 when the contacts 48 are closed.

If the voltage-to-resistance ratio of the power supply 51 and resistor 54 is higher than the voltage-to-resistance ratio of the power supply 53 and its circuit (including the glow valve 45, but not including the power supply 51 or resistor' 54) the opening of the contacts 48 of the relay 41 serves to increase the voltage-to-resistance ratio of the circuit containing the glow valve 45. An increase of this ratio increases the current through the glow valve and coil 46.

The extra current supplied in this manner to the coil 46 hastens the further operation of the relay 41. The next subsequent opening of the interrupter or timer opens the circuit through the coil 46 and the glow valve 45 so as to interrupt the current therethrough. This extinguishes the glow valve and deenergizes the coil 45 of the relay 41. The relay, therefore, "releases and in so doing again closes the contacts 48. This removes the potential of the power supply 51 from the circuit through the glow valve 45 so that upon a subsequent closing of the interrupter 50, the potential of the power supply 51 will not be impressed upon the glow valve 45. As a result of the operation of the relay 41, the load contact 49 has closed and opened its load circuit to effect the desired control function. Should a signal be transmitted from the photoelectric cell II, at a time when the contacts of the interrupter II are open, it will be ineffective to ignite the glow valve 45.

It is not necessary to describe here the complete control scheme for controlling the register of the strip material II with respect to the operation of the interrupter 5. since the general arrangement of such control schemes is well known and the same forms no part of our present invention. The control apparatus used with our system just described, should be arranged to so operate in response to the operation of the contacts 49 as to advance the strip llwith respect to the operation of the interrupter 50. The strip ll should be arranged normally to run slightly slow so that it lags behind the operation of the interrupter 50 and requires an occasional advance to keep it in register. This causes the apparatus of the present invention to time" the movement of the strip material I! with respect to the closing operation of the interrupter 50. The interrupter 50 should be driven synchronously, as by means of gears or the like, with that part of the processing machine with which it is desired to register the separate impressions or the separate gauge marks l5 of the strip material it. In Fig. 2 we have illustrated a slightly different photoelectric glow valve system embodying our present invention. The photoelectric cell and its amplifier in the system of Fig. 2 are identical with the corresponding apparatus of the system of Fig. 1, and therefore are not shown fully in Fig. 2. The corresponding parts are indicated by the same reference numerals. secondary winding 42 of the impulse transformer 22 is connected in series with the diode glow valve 45, the coil iii of a relay 62, the interrupter 50 and a power supply 65 having a positive terminal 66 and a negative terminal 61. comprising the normally open contact gap 63 of the relay 62 and the power supply 68 is connected across the terminals of the secondary winding 42 of the impulse transformer 22. The polarity of the power supply 68 is such with respect to that of the power supply 65 that their voltages add in the series circuit through them both, which circuit is established when the contacts 63 close. Load contacts 64 operated by the relay 62 may be connected to other apparatus for controlling it in a known manner. Each of the power supplies 65 and 68 includes a diode rectifier and a filter net.

In operation, the photoelectric cell and its amplifier, (not shown in Fig. 2) operate in the same manner as do the corresponding pieces of apparatus of Fig. 1 to produce a series of highvoltage signals in the secondary winding 42 or the impuse transformer 22.- If a signal of the proper polarity for adding itself to the voltage of the power supply $5, is produced when the interrupter 50 is closed, the glow valve 45 ignites. A weak flow of current driven by the voltage of the power supply 65 traverses the glow valve 45 and the coil BI 01. the relay 62. This causes the relay 62 to begin its operation, whereupon it closes its contacts 63 to close the shunt path around'the secondary winding 42 of the transformer 22. This permits the current through the glow valve 45 to bypass the comparatively high resistance of the winding 42 by flowing through the low resistance of the shunt path established by the closing of the contacts 53. This serves to lower the resistance of the glow valve circuit, and also to add thereto the In Fig. 2, the.

A shunt circuit voltage of the power supply 68 to aid that of the power supply 65. Either of these effects alone would serve to increase the current flowing through the valve 45 and the relay coil 6|. The two effects together permit the current to be increased to the full capacity of the valve 45. This increased current hastens the operation of the relay 62. Thereafter, the interrupter 50 opens its contacts so as to terminate the glow operation. This deenergizes the coil 6| of the relay 62 causing it to release, and in so doing to open its contacts 63. This restores the coupling of the valve to its signal input (the winding 42 of the impulse transformer 22) so that a subsequent signal produced at a time when the contacts of the interrupter 50 again are closed will produce another glow operation of the valve 45. The relay 62, in operating, has closed and opened its load contacts 64 to control its load circuit.

It is to be observed that the contacts 63 of the relay 62, in establishing the shunt circuit across the signal input of the valve 45 I the winding 42) served to remove from the glow current circuit a comparatively high resistance and to add thereto additional voltage so as to materially increase the voltage-to-resistanc-e ratio thereof. Obviously the power supply 68 may be omitted and the contacts 63 employed merely to short circuit the winding 42. Merely removing this high resistance from the glow valve circuit produces an increase of the voltage to resistance ratio of the glow valve circuit.

The system of Fig. 1 may be preferred under certain conditions to the system of Fig. 2 because it employs normally closed contacts (contacts 48) to provide the current boosting function. In certain types of relays, normally closed contacts can be made to operate on a slight initial motion of the relay armature inore easily than can normally open contacts.

Under other conditions the system of Fig. 2 may be preferred because it actually removes the major high resistance, namely the transformer winding, from the glow valve circuit, and therefore permits a greater voltage resistance ratio with the same total voltage in the two power supplies. In fact, this provides ample current in many instances without the use of the power supply 68.

Fig. 3 illustrates the preferred embodiment of our present invention. Therein, a photoelectric cell H0 is illuminated by a lamp or light source III. The light from the lamp III is focused by a lens I I2 into the plane of a moving web of strip material II 3, the light passing therethrough to irradiate the light sensitive cathode H4 of the photoelectric cell H0. The web H3 carries a series of relatively opaque reference marks H5 which are so arranged as to pass into the light beam as the strip progresses so as to diminish or substantially interrupt the illumination of the cathode H4 of the photoelectric cell H0. The cathode H4 and anode H6 of the photoelectric cell are connected to the in-put terminals H1 and H8 respectively of an amplifier and relay unit indicated generally by the dotted outline I20. Terminal H1 is grounded to the chassis. The amplifier comprises a pentode amplifying valve I2I coupled to an impulse transformer I22.

Power for the operation of the entire system including the pentode amplifier is obtained from a transformer which is designated generally by the reference numeral I23. The power supply comprises a full wave rectifier I24, a tapped secondary winding I of the transformer I22 and a conventional filter net. The positive terminal of the out-put of the power supply is designated by the reference numeral I26 and the negative terminal is grounded at I21. Connected between the positive terminal I26 of the power supply and ground are a pair of series connected resistors I34 and I36 which constitute a bleeder. These resistors have taps I39 and I31 respectively to permit an adjustment of the potentials supplied to the amplifying valve I2I. The anode I29 of the pentode amplifying valve I2I is connected to the tap I39 of the resistor I34 through the primary winding I30 of the impulse transformer I 22 and a milliammcter I33. The screen grid ,I3I of the pentode I2I is connected directly to the tap I39 so that it remains at substantially constant potential for shielding the control grid I 32 from the effect of varying potentials of the anode I29 in a manner well known in the art.

A high resistance I35 is connected in series being connected to terminal I21, and the anode H6 thereof being connected to the resistor I35. The anode H6 of the cell is connected, also, to the control grid I32 of the pentode amplifier I2I. The tap I31 of the bleedcr resistor I36 is connected to the cathode I38 of the amplifier Iii. An adjustment of the tap I3l of the blceder rcsistor I36 serves to control the difference of the potential between the cathode I38 and control grid I32 of the valve. This is commonly referred to as the bias potential of the valve. The tap I31 should be adjusted to provide a low anode current as shown by the milliammeter I33 when.

the light beam is unobstructed by any of the reference marks H5. Thus if the pentode valve I2I saturates at a current in the neighborhood of 15 milliamperes, the tap I31 may be set to bring this current to about 1 milliampere. When one of the reference marks H5 darkens the photoelectric cell H0, the anode current of the valve I 2I will increase.

A cathode grid I40 of the valve which serves to suppress secondary emission from the anode I29 in valve I2I is connected directly to the cathode I38 within the valve itself. A filament heater I4I for the cathode I38 of the valve I2I r receives power from one of the windings of the transformer I23.

The impulse transformer I22 has an exceed ingly high step-up ratio. It is desirable to secure as much signal amplification as possible in the transformer I22 and to this end it is given as high an impedance ratio as is possible. As is well known, the impedance that may be provided in such a winding is limited in part by the presence of capacity between the individual turns of the winding.

The secondary winding I42 of the transformer is connected in a circuit which may be traced as follows: Beginning at the ground connection at an interrupter I50, through the contact gap of the interrupter I50, thence through the winding I42 of the transformer I22, thence through a diode glow valve I45 and the coil I46 of a relay I41 to the power supply. The connection to the power supply is made at an adjustable tap I of a bleeder I 6| to permit an adjustment of the voltage which is impressed across the glow valve I45 during its idle or non-glowing period. The circuit is completed through the ground connection of the power supply. The glow valve I45 is 7 of the cold cathode type. An electronic rectifier I65, such asa diode having a hot cathode and containing mercury vapor, is shunted across the terminals of the secondary winding I42 of the impulse transformer I22, its anode I66 being connected to that terminal of the winding I42 which faces the positive terminal of the power supply in the circuit through the glow valve I45 so that a substantial portion of the current from the power supply that passes through the glow valve I45 will be shunted around the winding I42 through the rectifier I65. It is to be observed that the system is so arranged as respects the polarity of the power supply and as respects the respective locations of the timer I50, transformer winding I42, glow valve I45 and relay coil I46 in the glow valve circuit as to impose a minimum shunt capacity across the terminals of the winding I42. Thus, inasmuch as one terminal of the transformer winding I42 is connected to ground through the interrupter I50, precaution is taken to avoid connecting to the other terminal of the winding I42, any object having a high capacity to ground, such as for example, the cathode of the valve I65 which is connected to a secondary winding of the transformer I23. The ungrounded terminal of the transformer winding I42 is connected only to the anode of the rectifier I66 and the cold cathode of the glow valve I45 both of which have comparatively low capacities to other elements of the apparatus. If a glow valve having a hot cathode requiring heater connections to the transformer should be employed, it would be desirable to use a rectifier shunting the winding I42 having a cold cathode, and to connect the anode of the glow valve and the cathode of the rectifier to the ungrounded terminal of the transformer winding I42, the power supply connections being changed to suit. The contacts I of the relay I" are arranged to be operated in response to the flow of current through the coil I46 when valve I glows. These contacts may be connected to control a load circuit in any known manner for providing the desired control function. g

In operation, the photoelectric cell IIO generates a signal each time that one of the reference marks II5 of the strip II 3 enters or leaves the beam of light from the light source III, which is focused to illuminate the cathode II4 of the photoelectric cell IIO through the web H3. The signal generated bythe photoelectric cell in response to each of the reference marks II5 entering the light beam will be amplified by the pentdde valve I2I and will produce an abrupt increase of current in the primary winding I30 of the transformer I22. The signal produced in photoelectric cell IIO when each reference mark I I5 leaves the light beam, will produce an abrupt decrease in the current in the winding I30.

These abrupt changes in the primary current of the transformer I22 produce high voltage signals in the secondary winding I42 thereof, having opposite polarities. Both of these signals will tend to impress'voltages across the terminals of the glow valve I45. One of these signals will be in such direction as to oppose the voltage of the power supply and will tend to reduce the voltage impressed across the electrodes of the glow valve I45. This signal will encounter a low impedance through the rectifier I65 which shunts the secondary winding I42. The other signal, being of opposite polarity, will add itself to the voltage of the power supply so as to increase the total voltage impressed upon the electrodes of the glow valve I 45. This signal encounters the high impedance of the rectifier I65, and since the rectifier I65 is of the electronic type, none of thesignal current passes therethrough. Consequently'the full signal strength is available to be impressed across the terminals of the glow valve I45. The sum of the signal voltage and the voltage of the power supply is sufficient to ignite the valve I45, that is to initiate its glow operation, and once the glow is initiated, it becomes self-sustaining at voltages considerably below that required forignition. The voltage of the power supply is less than the ignition voltage but is suflicient by itself to maintain the glow operation of the valve I45. That is, the voltage of the power supply is in excess of the extinguishing voltage of the glow valve I45. Once the valve I45 begins to glow the power supply will maintain the glow operation without the aid of the signal so that the glow persists after the termination of the signal. The

current fiowing from the power supply through the glow valve I45 encounters the low impedance of the rectifier I65 and the greater portion of the current fiows therethrough rather than through the winding I42 of the transformer.

Inasmuch as the shunt path through the rectifying valve I65 presents a much lower impedance to the current from the power supply than does the winding I42 of the signal transformer I22, the action of the rectifier valve I65 in shunting the glow current therethrough effectively reduces the voltage to resistance ratio of the circuit through the glow valve. The rectifier I65 brings about this change in the condition of the glow valve I45; and it maintains the changed condition during the time that the valve I45 is glowing and so long as current flows through the rectifier I 65 in the direction for taking power from the power supply.

The current passed by the power 'supply through the glow valve I45 and rectifying valve I65 also traverses the coil I46 of the relay I41 causing that relay to operate its contacts to effect the desired control function.

Subsequentl when the interrupter I50 opens its contacts, it completely interrupts all circuits through the glow valve I45 so as to terminate the glow operation thereof. When the interrupter I50 thereafter closes, the valve I45 does not resume its glow operation because the voltage impressed across it by the power supply is less than its ignition or striking voltage.

Thus, we have provided an electronic device shunting the signal input of the glow valve network, which device presents a high impedance to the voltage of the signal when the glow valve is not glowing and which responds to the glow operation of the valve to shunt effectively the high resistance of the signal input.

The system of Figure 3 constitutes the preferred embodiment of our present invention. The system of Figure 3 is superior to the systems of Figures 1 and 2 in that it is faster and more dependable in operation. The action of the valve I is electronic and it responds directly and immediately to the ignition of the glow valve I45. That is, it responds directly to the initiation of the glow operation of the valve I45. Consequently there is no appreciable delay or elapse of time between the ignition of the glow valve I45 and the boosting action of the rectifying valve I65. On the other hand, the actions of the relays of the systems of Figures 1 and 2, are in part mechanical and an appreciable delay occurs in each case between the initiation of the flow of current resulting from the ignition of the glow valve 45 and the operation of the booster" contacts of the relay. Each of the systems of Figures 1 and 2 is dependent upon its relay properly and successfully executing its initial operation on the weak initial glow current in order to accomplish the boosting of the current in the glow valve circuit, while the system of Figure 3 boosts the current regardless of the operation of its relay.

Figure 4 illustrates diagrammatically, and for the purpose of illustration, a modification of the glow valve circuit net of the system of Figure 3. Those parts of Figure 4 which have corresponding parts in the system of Figure 3 are indicated by the same reference numerals. The circuit net of Figure 4 consists of 3 branches as follows: The first branch includes a signal means or secondary winding I42 of the signal transformer I22, and a battery or power supply I10. The second branch includes the rectifying valve I65 and a battery or power supply I1 I, and the third branch includes the glow valve I45, the coil I46 of the relay I41, the interrupter I50 and the battery or power supply I12. The batteries I10, HI, and I12 are marked to indicate their polarities, and their polarities are such that in the closed circuit which includes the glow valve I45, and the signal means I42, the voltages of the batteries I10 and I12 therein add. This circuit is the ignition circuit of the glow valve I45. Also, in the circuit through the glow valve I45, and the rectifying valve I65, the voltages of the batteries HI and I12 therein add. This is the sustaining circuit of the glow valve I45. The sum of the voltages of the batteries I10 and I12 must be less than the ignition voltage of the valve I45, and the signal voltage appearing in the winding I42 of the transformer I22 must be of such value that when it is added to the voltages of the power supplies I10 and I12 it is sufficient to ignite the valve I45. Also the sum of the voltages of the power supplies Ill and I12 must be in excess of the extinguishing voltage of the glow valve I45. Generally it will be preferred to eliminate the two batteries I10 and I1 I, in which case the circuit of Figure 4 reduces to the circuit of the system of Figure 3.

While we have shown and described certain specific embodiments of our invention, it will be apparent to those skilled in the art that the same are by way of illustration only and are capable of various modifications. Therefore, we do not wish to be limited except by the scope of the appended claims.

We claim:

1. In combination in a system of the class described, a glow valve having an anode and a cathode, an anode-cathode circuit therefore including said anode and cathode, a. power supply in said circuit, and means other than said glow valve responsive to a flow of current from the anode to the cathode of said glow valve for increasing the current between said anode and cathode.

2. In combination in a system of the class described, a glow valve having an anode and a cathode, an anode-cathode circuit therefore including said anode and cathode, a power supply for applying voltage to said circuit, means for igniting said valve, a relay having a coil in said anode cathode circuit and means including contacts of said relay responsive to current in said anode cathode circuit for increasing the voltage applied to said circuit.

3. In combination in a system of the class described a glow valve 'having an anode and a cathode, an anode-cathode circuit therefor including said anode and cathode, a. power supply in said circuit, a relay having a coil in said circuit, signal input means in said circuit for igniting said valve and contacts operated by said relay in response to the current which flows in said circuit when said valve is ignited for short cir cuiting said signal input means.

4. In combination in a system of the class described, an electronic amplifier, an impulse transformer having a primary winding connected to receive power from said amplifier, said transformer having, also, a secondary winding, and an electric glow valve having an anode and a cathode, an interrupter, a relay having a coil and normally open contacts, and a power supply having a voltage sufficient to sustain operation of said glow valve but insufficient to initiate a glow operation thereof, said secondary winding, glow valve, power supply, relay coil and interrupter being connected in series, said normally open contacts of said relay being included in a current path shunting said secondary winding.

5. In combination in a system of the class described, an electric glow valve having an anode and cathode, a direct current power supply having a voltage below the ignition voltage of said valve but above the extinguishing volt thereof, a high resistance signal means adapted to provide a signal voltage sufficient when added to the voltage of said power supply to ignite said valve, said power supply, the anode and cathode of said glow valve and said signal means being connected in series so that said voltages of said power supply and signal means add to ignite said valve, and means having an unsymmetrical impedance shunting said signal means for presenting a low impedance to current in the direction therethrough of said voltage of said power supply and for presenting a high impedance to currents therethrough in the direction of said signal voltage.

6. In combination in a system of the class described, an electric glow valve having an anode and a cathode, a direct current power supply having a voltage below the ignition voltage of said valve but above the extinguishing voltage thereof. a second valve which permits current to flow in only one direction therethrough, circuit connections providing a series circuit for the flow of current through said power supply in the direction of its voltage, through said second valve in the direction in which it passes current and through said glow valve from the anode to the cathode thereof, and signal means adapted to provide a voltage for igniting said glow valve and having two terminals, one of said terminals being connected to said series circuit at a first point between said second valve and said glow valve, the other of said terminals being connected at a second point of said series circuit which is between said glow valve and said second valve but on the opposite sides of both said valves from said first point.

7. In combination in a system of the class described, an electric glow valve having an anode and a cathode, a direct current power supply for supplying direct current at a voltage below the ignition voltage of said glow valve but above the extinguishing voltage thereof, said power supply comprising an alternating current supply, a rectifier and a filter, a high impedance signal means adapted to provide a voltage for igniting said valve, a relay, an interrupter and a second rectifier, the anode of said second rectifier being connected to the cathode of said glow valve and to one terminal of said signal means, said power supply, relay and interrupter being connected in a series group between the anode the anode of said glow valve-and the cathode of said rectifier, the other terminal of said signal means being connected to said series group.

8. In combination in a system of the class described, means for generating an impulse, an electronic amplifier for amplifying said impulse, a step up transformer having a primary winding for receiving the amplified impulse, said transformer, also, having a secondary winding, a glow valve connected to said secondary winding to receive the amplified and stepped up impulse therefrom, said valve being adapted to ignite upon receiving an impulse of sufficient voltage, a power supply connected to said glow valve for sustaining a glow operation of said valve when said valve ignites, a relay connected to said valve and responsive to a sustained glow operation of said valve, a rectifier shunting said secondary winding of said transformer so as to present its lower resistance to the current of said glow valve during a sustained glow operation thereof, and means for interrupting the circuit through said glow valve.

9. In combination in a system of the class described an electric glow valve having an anode and a cathode, a direct current power supply having a voltage below the ignition voltage of said valve but above the extinguishing voltage thereof, a high resistance signal means adapted to provide a signal voltage sufficient when added to the voltage of said power supply to ignite said glow valve, said direct current power supply, the anode and cathode of said glow valve and said signal means being connected in series in a series circuit so that said voltages of said power supply and said signal means add to ignite said valve, a shunt path connected between (1) a first point of said series circuit between said glow valve and said signal means and (2) a second point of said series circuit between said glow valve and signal means but on the opposite side of each said elements from said first point, and an electronic valve in said shunt path, said electronic valve in said shunt path being adapted to present a high impedance to the voltage of said signal when said glow valve is not glowing and to present a low impedance to the voltage of said direct current power supply when said glow valve is glowing.

10. In combination in a system of the class described, an electric glow valve having an anode and a cathode, a power supply having a voltage below the ignition voltage of said valve but above the extinguishing voltage thereof, a high impedance signal means adapted to provide a signal voltage sufilcient when added to the voltage of said power supply to ignite said glow valve, said power supply, the anode and cathode of said glow valve and said signal means being connected in series in a series circuit so that said voltages of said power supply and said signal means add to ignite said valve, a shunt path connected between (l) a first point of said series circuit between said glow valve and said signal means and (2) a second point of said series circuit between said glow valve and signal means but on the opposite side of each said elements from said first point, and an electronic device in said shunt path adapted to present a high impedance to the voltage of said signal means when said glow valve is not glowing, said electronic device being responsive to a glow operation of said valve effectively to shunt the high impedance of said signal means.

11. In combination in a system of'the class described an electric glow valve having a pair of electrodes, a power supply having a voltage below the ignition voltage of said glow valv'e but above the extinguishing voltage thereof, a second valve having electrodes and being adapted to conduct current only in one direction between its electrodes, circuit connections providing a series circuit for the fiow of current through said power supply, through said second valve in the direction in.which it passes current, and through said glow valve, and signal means adapted to provide a voltage for igniting said glow valve and having two terminals, one of said terminals being con nected to an electrode of said glow valve and to an electrode of said second valve, the other of said terminals being connected to a point of said series circuit which is between said glow valve and said second valve but on opposite sides of both said valves from the connection to said first mentioned electrodes, said glow valve and said second valve connected to said first terminal of said signal means as aforesaid being so arranged as respects the polarities thereof that said valves and circuit connections therefor impose a minimum capacity shunt across said terminals of said signal means.

12. In combination in a system of the class described an electric glow valve having a pair of electrodes, a power supply having a voltage below the ignition voltage of said glow valve but above the extinguishing voltage thereof, a second valve having electrodes and being adapted to conduct current only in one direction between its electrodes, circuit connections providing a series circuit for the flow of current through said power supply, through said second valve in the direction in which it passes current, and through said glow valve, one of said valves having a cold cathode, the anode of the other of said valves being connected to said cold cathode, and signal means adapted to provide a voltage for igniting said glow valve and having two terminals, one of said terminals being connected to said cold cathode, the other of said terminals being connected to a point of said series circuit which is between said glow valve and said second valve but on opposite sides of both said valves from the connection of the first terminal to said cold cathode.

13. In combination in a system of the class described, an electric glow valve having an anode and a cold cathode, a direct current power supply having a voltage below the ignition voltage of said glow valve and above the extinguishing voltage thereof, said direct current power supply comprising a power transformer, a first rectifier and a filter, a second rectifying valve having an anode and a thermionic cathode, signal means adapted to provide a voltage for igniting said valve and having two terminals, an electric power supply including a winding of said power transformer for heating the thermionic cathode of said second rectifying valve, said cold cathode of said glow valve being connected to the anode of said second rectifying valve and to one terminal of said signal means, and circuit connections including said direct current power supply between the anode of said glow valve and the thermionic cathode of said second rectifying valve, said connections being so arranged as respects the polarity of said direct current power supply that the voltage of said direct current power supply tends to pass a current through said glow valve from the anode to the cathode thereof, the other terminal of said signal means being connected to said circuit connections. a

14. In combination in a system of the class described, an electric glow valve having an anode and a cathode, a power supply having a voltage below the ignition voltage of said glow valve but above the extinguishing voltage thereof, ignition means for igniting said valve, said power supply and ignition means being connected in an electric circuit with the anode and cathode 01 said glow valve, and means other than said glow valve, power supply and ignition means, responsive to a flow of current between the anode and cathode of said glow valve for increasing the current between said anode and cathode.

15. In combination in a system of the class described, an electric glow valve having an anode and a cathode, a power supply having a voltage insumcient to ignite said valve but suiiicient to sustain a glow operation thereof, a high impedance signal means adapted to provide a signal voltage suflicient when added to the voltage of said power supply to ignite said valve, said power supply, the anode and cathode of said glow valve, and said signal means being connected in series so that said voltages add to ignite said 'glow valve, and means responsive to a glow operation of said glow valve for shunting the high impedance of said signal means.

' 16. The combination of claim 15, wherein said last means consists of an unsymmetrical impedance device whereby it presents a high shunt impedance to a signal but a low series impedance to the current drawn by said glow valve when glowing in response to said signal.

ARCHIE J". McMAsTEa. KARL H. SOMMERMEYER. 

